1. Field of the Invention
The present invention relates to a sheet handling apparatus with a switchback section for selectively switching the conveyance direction of sheets.
2. Description of the Related Art
As a sheet handling apparatus of this type, a reverse control apparatus is known. This reverse control apparatus has a sensor for sensing the length of sheets in a first conveyance direction, and a reverse section for reversing the conveyance direction of the sheets into a second direction to cause the adjacent sheets to be forwarded in the second direction with the same gap therebetween (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2004-175507).
More specifically, in the reverse control apparatus, the length of each sheet to be fed to the reverse section is detected, and the pull-in amount of each sheet is adjusted based on the detection result, with the result that the gaps between adjacent sheets sent from the reverse section are made equal.
However, in the reverse control apparatus, it is assumed that the conveyance rate of sheets is constant between various sheet handling apparatuses. Therefore, when the conveyance rate is changed for some reason, or when the apparatuses employ different conveyance rates, the gaps between sheets sent from the reverse section cannot be kept constant, which reduces the reliability of the apparatus. For instance, if the conveyance belt for conveying sheets comes loose with time, or the load applied to the belt is varied, the conveyance rate may well be changed.